The controversial German anatomist Gunther von Hagens last night agreed to return seven corpses to China after admitting that the bodies used in his exhibitions might have come from executed prisoners.

Professor Von Hagens, whose show Body Worlds provoked fascination and disgust when it opened in London two years ago, said the corpses would now be buried. His statement follows a damning exposé this week by the German magazine Der Spiegel.

It revealed that at least two corpses out of some 647 stored by the anatomist at his centre in China had bullet holes in their skulls. Splashing the story on its cover under the headline Dr Death, the magazine this week produced damning email correspondence from Prof Von Hagens' Chinese manager, Sui Hongjin.

In December 2001 Dr Hongjin boasted that he had obtained the bodies of a "young man and young woman" who had "died" that morning. The pair were "fresh examples" of the "highest quality", the doctor said - and had been killed by a shot to the head.

Speaking yesterday Prof Von Hagens, who earned the tabloid soubriquet Dr Frankenstein after performing a live televised autopsy on a German alcoholic in 2002, said: "I have told my Chinese employees that they can't accept bodies that were executed."

He added: "I can't prove the bodies weren't executed, but I believe they weren't." He said he received his bodies from Chinese officials but could not be sure of their origins.

He said he only discovered last week that seven corpses in his collection had head injuries. The fedora-wearing scientist now lives in the Chinese city of Dalian and employs 200 people to dissect and preserve corpses at a centre.

The centre is close to three prison camps, which are home to political detainees and members of the banned Falun Gong movement. According to Amnesty International, China's communist authorities executed 2,468 people in 2001 by shooting them in the head or the back of the neck. Prof Von Hagens has previously been accused of buying the corpses of prisoners, homeless people and the mentally ill in Russia - a charge he denies.

So far nearly 14 million people in Britain, Germany, Japan and Korea have seen the travelling corpse show. The exhibition shows the human body in a series of poses: one figure rides a rearing horse, while in another a pregnant woman reclines. Yesterday Prof Von Hagens, whose show has just opened in Frankfurt, insisted that all the people who appear in his exhibition had signed releases prior to their death.

Since the inception of his Body Worlds exhibits, protesters have pointed out that Prof Von Hagens' work is in bad taste and insults the dead. The show in Frankfurt, which opened last week, was met with criticism by the Lutheran church, which promised a prayer vigil and a series of lectures in response.

At a London show, two visitors vandalised parts of the exhibit on separate occasions, and in Munich last year, city leaders would allow the show only after Prof Von Hagens agreed to remove some of the more dramatic exhibits, including a corpse posed like a fencer.

Karl Hafen, who was among a small group of protesters at the press conference, carried a sign calling Prof Von Hagens' work immoral. "I have to say, anyone who does business with Russia or China, that person must know that these governments are corrupt," he said. "If you are buying cheap specimens in China, that should tip you off."